Knox grew up in Birmingham, AL, where as a high-school senior at Huffman High in Birmingham he was honored as a U.S. Presidential Scholar.[1][2] He went to college at the University of Alabama at Birmingham (UAB). He was recruited to UAB as a member of the inaugural class of the UAB Honors Program, now the University Honors Program, and served on its Honors Council for three years. He was UAB's first national finalist in the Rhodes Scholar competition and later served as an ex officio member of the UAB Rhodes Committee, assisting UAB Rhodes candidates up to and including UAB's first winner, Neel Varshney, in 2000. As a graduating senior at UAB in 1988, Knox won both a National Science Foundation Graduate Research Fellowship and a Phi Kappa Phi Fellowship, and was a national finalist for the Omicron Delta Kappa National Leader of the Year Award.[3][4]

In 1997, inventor Harlan Brothers sent some college-level expression for e to National Public Radio's program "Science Friday".[5] Knox's wife Pam, an intern at "Science Friday" during Knox's post-doc at NASA/GISS, told them to Knox, who confirmed them.[3][5] Together, they derived several formulae to calculate e. The formulae involve applying Bernoulli's standard result that (1 + 1/n)n approximates e when n becomes large, to the formula , which is the basis of the popular bilinear transform.

Since 1995 Knox has performed research on clear-air turbulence (CAT), in particular CAT forecasting. In 2008, he co-authored (with Don McCann, and Paul Williams of the University of Reading) an article in the Journal of the Atmospheric Sciences describing a new method of CAT forecasting that received international media attention.[6][7] In 2010, Knox was honored by the National Weather Association with the T. Theodore Fujita Research Achievement Award for his CAT forecasting research.

Knox writes popular articles and books about meteorology, including the award-winning[8]Meteorology: Understanding the Atmosphere with Steven A. Ackerman of the University of Wisconsin-Madison.

In April 2012 Knox was the only geography professor in the nation, and one of only two atmospheric scientists, included in The Princeton Review's first-ever "Best 300 Professors" list and book.[9]

In November 2014 Knox was honored as the Georgia Professor of the Year by the organizations CASE and the Carnegie Foundation for the Advancement of Teaching in the US Professors of the Year ceremony at the National Press Club in Washington, DC. He was the first UGA professor named the state's Professor of the Year in a decade, and the first atmospheric sciences professor to be named any state's Professor of the Year in a quarter-century.[10]

In January 2015 Knox was extended an invitation to join the organization Faculty Row,[11] a private global network of accomplished academics, as one of its approximately 1,600 "Super Professors" worldwide.

Knox is currently an Associate Professor in the Geography Department at the University of Georgia and since 2004 the Undergraduate Coordinator for its Atmospheric Sciences Program.[12] Since 2011 Knox has served as Faculty Advisor for the Demosthenian Literary Society, UGA's oldest student organization (founded in 1803).[13]